Before being elected a TD, she had been a high-profile Chair of the Council for the Status of Women from 1988 to 1992.

She was the Fine Gael candidate at the 2007 general election for the Dublin Mid-West constituency, but was not elected.[7] She was elected to the Seanad in July 2007. On 12 September 2007, she was appointed leader of the Fine Gael group in Seanad Éireann, and was also Fine Gael Seanad spokesperson on Health and Children, and a member of the Fine Gael Front Bench.

Fitzgerald has spoken out in support of young families, and believes the government should take a more proactive role in helping parents and children. "I feel so strongly about the State taking a more proactive role around childcare, paternity leave and parental leave," she noted. "I do want to see us getting to the place where the State is more supportive when it comes to childcare. We have been slow enough on that."[11]

In early 2016 when gangland activity became an issue in Dublin, Fitzgerald committed that there would be a permanent armed response unit in Dublin.[12]

On 6 May 2016, Fitzgerald was reappointed the Minister for Justice and Equality. She was also promoted to the position of Tánaiste (Deputy Prime Minister) by TaoiseachEnda Kenny.[13][14]